Band-edge superconductivity

TL;DR

This paper demonstrates that superconductivity can emerge in semiconductors with Mexican hat band structures when interactions are strong enough, even without the band crossing the Fermi level.

Contribution

It introduces a mechanism for superconductivity arising from a band insulator with Mexican hat dispersion near the band edge, emphasizing the role of strong interactions.

Findings

Superconductivity occurs near the band edge in Mexican hat band structures.

Strong interactions are necessary for superconductivity in this scenario.

Semiconductors with cubic symmetry and strong spin-orbit coupling are potential candidates.

Abstract

We show that superconductivity can arise in semiconductors with a band in the shape of a Mexican hat when the chemical potential is tuned close to the band edge, but not intersecting the band, as long as interactions are sufficiently strong. Hence, this is an example where superconductivity can emerge from a band insulator when interactions exceed a threshold. Semiconductors with simple cubic symmetry point groups and with strong spin-orbit coupling provide an example of a system with such band dispersion.